Truelab LND-2 Zahn-Type Efflux Viscometer (No. 3–No. 6 Cups)

Overview

The Truelab LND-2 Zahn-Type Efflux Viscometer is a precision-engineered benchtop instrument designed for rapid, repeatable determination of kinematic viscosity in low-to-medium viscosity Newtonian and near-Newtonian liquids—primarily coatings, varnishes, lacquers, inks, and solvent-based resins. Based on the standardized efflux principle, the LND-2 measures the time required for a fixed volume of sample to drain through a precisely dimensioned orifice under gravity. This method directly correlates efflux time (in seconds) to kinematic viscosity (mm²/s or cSt), following empirical calibration curves defined in ASTM D1200 and ISO 2431. Unlike rotational or capillary viscometers, the LND-2 requires no motorized drive, temperature bath, or complex fluid handling—making it ideal for high-throughput QC labs where speed, simplicity, and regulatory traceability are critical. Its design adheres to Good Laboratory Practice (GLP) fundamentals: all cups are manufactured to strict dimensional tolerances (orifice diameter ±0.01 mm, cup geometry per ASTM Annex A1), and each cup is individually calibrated against NIST-traceable reference oils.

Key Features

• Zahn-style stainless-steel efflux cups (No. 3, No. 4, No. 5, and No. 6) supplied as standard—each with laser-etched identification and certified dimensional compliance.
• Benchtop fixed-mount configuration ensures consistent vertical alignment and eliminates operator-induced tilt error during timing.
• High-contrast digital stopwatch integration (optional accessory) enables precise efflux time capture with 0.01 s resolution—critical for meeting ASTM D1200 repeatability requirements (≤1% RSD for duplicate runs).
• No internal temperature control; validated for use at controlled ambient conditions (20–25 °C, <65% RH), aligning with ISO 2884-1 and ASTM D1200 environmental specifications.
• Minimal maintenance architecture: fully disassemblable cups, corrosion-resistant 316 stainless steel construction, and non-clogging orifice geometry optimized for pigmented and thixotropic formulations.
• Compliant with multiple national and international standards: ASTM D1200 (Zahn cup), ISO 2431 (efflux viscometers), GB/T 1723–1993 (Chinese standard for coating viscosity), and JIS K 5600-2-4.

Sample Compatibility & Compliance

The LND-2 is validated for clear, low-sediment, low-particulate liquids with apparent viscosities between 6.6 mm²/s (No. 3 cup) and 684 mm²/s (No. 6 cup). It is routinely employed for QC testing of architectural paints, automotive refinish coatings, coil coatings, and UV-curable formulations. While not suitable for highly shear-thinning, gel-like, or particle-laden systems (>5 µm suspended solids), its efflux methodology remains the globally accepted first-line screening tool for batch release in coating manufacturing. All test procedures conform to ISO/IEC 17025 documentation requirements when paired with calibrated timers and certified reference oils. The instrument supports audit-ready recordkeeping: efflux time, cup number, ambient temperature/humidity, operator ID, and lot traceability can be logged manually or via optional LIMS-compatible data export modules.

Software & Data Management

The base LND-2 operates without embedded firmware or proprietary software—ensuring long-term operational stability and eliminating cybersecurity vulnerabilities associated with connected instruments. However, Truelab provides a free Windows-compatible desktop utility (ViscoLog v2.1) that accepts manual or stopwatch-synced efflux times and automatically converts them to kinematic viscosity using cup-specific ASTM D1200 polynomial equations. The software generates PDF test reports compliant with 21 CFR Part 11 (electronic signatures, audit trail, user access levels) when deployed on validated IT infrastructure. Raw data files (.csv) retain full metadata—including timestamp, cup ID, operator code, and environmental notes—for integration into enterprise quality management systems (QMS) such as TrackWise or MasterControl.

Applications

• Batch-to-batch viscosity consistency verification prior to canning or dispensing.
• In-process monitoring during resin synthesis or pigment grinding stages.
• Supplier raw material acceptance testing (e.g., alkyd resins, acrylic emulsions, solvents).
• Technical service support for field viscosity adjustment recommendations (e.g., thinning agent dosing).
• Educational laboratories teaching fundamental rheological concepts and standard test methods.
• Regulatory submission dossiers requiring ASTM/ISO-aligned viscosity data (e.g., EPA, EU REACH, FDA colorant filings).

FAQ

What standards does the LND-2 comply with?
ASTM D1200, ISO 2431, GB/T 1723–1993, JIS K 5600-2-4, and DIN 53211.
Can the LND-2 measure non-Newtonian fluids?
It provides an apparent viscosity value under low-shear gravity-driven flow; results should be interpreted as comparative QC metrics—not fundamental rheological parameters.
Is temperature control built into the instrument?
No. Per ASTM D1200, testing must occur in a temperature-stabilized environment (20–25 °C); external thermostatic chambers or air-conditioned labs are required for compliance.
How often should the cups be recalibrated?
Annually—or after mechanical damage, abrasive cleaning, or deviation exceeding ±3% against certified reference oils.
Does Truelab supply certified reference oils for verification?
Yes. NIST-traceable silicone oil standards (5, 10, 35, 100, 250, 500 cSt) are available with CoA and uncertainty statements.